(a) Field of the Invention
The present invention relates to a liquid crystal display (“LCD”) and a method of generating gamma voltages for an LCD and, in particular, to an LCD and a method of generating gamma voltages for an LCD for improving dynamic contrast of an image of an LCD by adjusting gamma voltages based on the brightness of an image.
(b) Description of the Related Art
Recently, as personal computers and television sets are lighter and slimmer, flat panel displays such as liquid crystal displays (“LCD”) have been developed and put into practice in various fields to replace cathode-ray tubes (“CRTs”).
LCDs display images by adjusting an electric field applied to liquid crystal material with dielectric anisotropy interposed between two panels, thereby controlling the transmittance of light passing through the panels.
LCDs have been used in notebook computers and desktop monitors. The users of computers have a desire to see motion pictures using display devices of the computers under improved multimedia circumstances. However, the currently used LCDs are inferior to the CRTs in dynamic contrast. Accordingly, in order to apply the LCDs for television sets, it is required to further improve the dynamic contrast of the LCDs.
Now, a typical LCD is described with reference to FIG. 1.
FIG. 1 shows an entire configuration of a conventional LCD.
As shown in FIG. 1, a conventional LCD includes an LCD panel assembly 1 having a plurality of pixels provided at the intersections of a plurality of gate lines and a plurality of data lines, a plurality of gate driving integrated circuits (“ICs”) 2 applying voltage signals for sequentially scanning the gate lines, a plurality of source driving ICs 3 applying voltage signals for image display to the data lines, a gamma voltage generator 5 having a plurality of resistors connected in series for generating a plurality of gamma voltages, a plurality of analog buffers 6 and 7 for providing the generated gamma voltages to the source driving ICs 3, and a timing controller 4 for performing gate on/off control as well as providing image data and other control signals for the source driving ICs 3.
In the above described LCD, the gate driving ICs 2 sequentially turn on the gate lines of the LCD panel assembly 1 under the gate on/off control of the timing controller 4. The source driving ICs 3 convert the image data from the timing controller 4 into voltage signals and then write the voltage signals to the pixels associated with the turned-on gate lines, on the basis of the control signals. The desired images are displayed in this manner.
A voltage signal for image display is generated by selecting appropriate one among the gamma voltages, which are provided by the gamma voltage generator 5 via the analog buffers 6 and 7, corresponding to the image data from the timing controller 4. That is, the source driving ICs 3 select the voltage signals to be applied to the LCD panel assembly 1 among the gamma voltages generated by the voltage division of the resistors of the gamma voltage generator 5.
However, the gamma voltages of a conventional LCD are fixed by the serially-connected resistors such that the brightness of an image implemented by these gamma voltages is also unchangeable. In other words, the fixed gamma voltages of the conventional LCD do not adjust the brightness of an image which is required when the image is brighter or darker.